title: Prevalence of breakthrough cancer pain: a systematic review and a pooled analysis of published literature.
abstract: BACKGROUND
  Despite the large body of literature on breakthrough cancer pain (BTcP), an accurate estimate of BTcP prevalence is still not available.
  
  
  OBJECTIVE
  To provide an estimate of BTcP prevalence and investigate the association between different prevalence rates and possible determinants.
  
  
  METHODS
  We conducted MEDLINE and EMBASE searches for studies published from 1990 to 2012 reporting data on BTcP prevalence in adult cancer populations. Pooled prevalence rates from observational studies with an acceptable methodological quality were computed. The association between BTcP prevalence and possible predictors was investigated using subgroup analyses and meta-regression.
  
  
  RESULTS
  Twenty-seven observational studies were identified. When quality criteria were applied, only 19 studies were included in the pooled analysis. The overall pooled prevalence was 59.2%, with high heterogeneity. The lowest prevalence rates were detected in studies conducted in outpatient clinics (39.9%), and the highest prevalence was reported in studies conducted in hospice (80.5%). The association between BTcP prevalence and other determinants such as publication year, age, gender, metastatic disease prevalence, or baseline pain intensity did not reach statistical significance.
  
  
  CONCLUSIONS
  In the context of a large between-studies heterogeneity, more than one in two patients with cancer pain also experiences BTcP, with some variability according to clinical and organizational variables.
authors.affiliation: Center for the Evaluation and Research on Pain (CERP), IRCCS Istituto di Ricerche Farmacologiche "Mario Negri," Milan, Italy; Istituto di Statistica Medica e Biometria "G. A. Maccacaro,", Università degli Studi di Milano, Milan, Italy. Electronic address: s.deandrea@yahoo.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Deandrea
authors.affiliation: Center for the Evaluation and Research on Pain (CERP), IRCCS Istituto di Ricerche Farmacologiche "Mario Negri," Milan, Italy.
authors.forename: Oscar
authors.initials: O
authors.lastname: Corli
authors.affiliation: Unit of Epidemiology, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Consonni
authors.affiliation: Center for the Evaluation and Research on Pain (CERP), IRCCS Istituto di Ricerche Farmacologiche "Mario Negri," Milan, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Villani
authors.affiliation: Istituto di Statistica Medica e Biometria "G. A. Maccacaro,", Università degli Studi di Milano, Milan, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Greco
authors.affiliation: Direzione Scientifica, IRCCS Arcispedale Santa Maria Nuova, Reggio-Emilia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Apolone
mesh_terms: D059390:Breakthrough Pain / Q000453:epidemiology* / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology* / Q000503:physiopathology* / Q000628:therapy; D015995:Prevalence
keywords: Breakthrough cancer pain; pooled analysis; prevalence; systematic review